A Novel Photoinimer for the Polymerization of Acrylates and Methacrylates

A new class of multifunctional photoinitiating system based on 3-(acryloyloxy)-2-hydroxypropyl methacrylate (AHM), N,N,N\u27-trimethylethylenediamine (TMED) and 3-benzoylbenzoyl chloride present in the same molecule has been synthesized and characterized by H-1 and C-13 NMR spectroscopy. This self-contained photoinitiator-monomer (photoinimer) was used to efficiently initiate polymerization of acrylates and methacrylates. Both rate of polymerization and percentage conversion increased with increase in initiator concentration. An increment in rate of polymerization observed when the benzophenone moiety was directly attached to the parent molecule (obtained from the Michael addition reaction between AHM and TMED) appears to be due to proximity effect: chemical bonding provides a high local concentration of both components of the photo-activated system involving benzophenone and a hydrogen atom source from an electron-rich tertiary amine. For the three initiating systems investigated, lowering the initiator concentration plays an important role; i.e., the polymerization rate for the chemically linked system was about two times faster than the mixed initiating system. (c) 2005 Wiley Periodicals, Inc